Black Bellied Whistling Duck, Black-bellied Whistling-Ducks spend more time than other ducks walking on land or perching in trees. Their length is from 18 to 20 inches with a wingspan from 30 to 37 inches. You can find these ducks foraging in fields, lawns, and shallow, freshwater ponds, mangroves, rivers and lagoons that often contain water hyacinth, water lilies, and cattails. Their average lifespan is 8 years.